1. Technical Field
This invention relates to communications between a diagnostic center and a remote site and, more particularly, to communications between a central diagnostic center and a remote monitoring site using only local telephone calls, thereby avoiding long-distance telephone charges.
2. Background Art
The ability to transfer data from a remote site to a central diagnostic center is an important and often indispensable function. There is a wide area of applications which require transfer of data from a remote site to be uploaded to a diagnostic center. For example, in the field of electric generation, diagnostic surveillance is often performed on the rotor of a turbine-generator set to detect the occurrence, location, and depth of cracks. Early diagnosis can prevent a catastrophic failure which may involve property damage and even personal injury, and can cause considerable electric generation down time. Similarly, in the aeronautic field, stresses on aircraft structures and engine parts are routinely monitored to detect defects and identify potential problem areas to predict possible failures before they occur. In the field of manufacturing, industrial controllers are routinely monitored to detect malfunctions. Suffice it to say, there are many applications which rely on diagnostic monitoring. In addition, for any given application there are usually many different remote sites to be monitored. Rather than have many different diagnostic stations, it is often more feasible that the diagnosing functions be controlled from a central diagnostic center, often located geographically far from the remote monitoring sites.
Communication systems for remote diagnostics presently transfer data via telephone lines. Therefore, a long distance telephone call is required from the remote site to the diagnostic center, or vice-versa from the diagnostic center to the remote site. This arrangement is quite costly, given the long distance telephone fees involved.
A particular need exists to provide a communication link between a remote site and a central diagnostic center which avoids long distance telephone services and the fees associated therewith.
In a preferred embodiment of the invention, a communication system is provided which uses public or private remote access infrastructure to facilitate wide-area communications between the remote site and the diagnostic center and which requires only local telephone calls. The diagnostic center and one or more remote sites at which monitored equipment is located are coupled to a wide area network (WAN). When data are to be transferred from a remote site to the central diagnostic center, the remote site initiates a local telephone call to a point-of-presence (POP) server on the WAN backbone. This could be an Internet Service Provider (ISP) in the case of the Internet, or an intranet POP server in the case of a private network. Data are then transferred to a computer in the POP server or anywhere on the network, as long as it is outside the so-called xe2x80x9cfirewallxe2x80x9d electronically isolating the diagnostic center from unwanted communications. To complete the transfer, the diagnostic center transfers the data from the POP server to the diagnostic center via the public or private wide-area network (the Internet or an intranet). The data transfer can take place either on a scheduled basis, or when an alarm condition is detected at the remote site. The central diagnostic center can prompt the remote site to connect to the POP server via a wireless paging service or a direct dial phone call.